Medical device for preservation of a corneal tissue, comprising an applanation lid, and optionally a trepanation lid

ABSTRACT

The invention relates to a medical device for preservation of corneal tissue (3) that has been obtained beforehand by sampling, the device comprising a base (11), at least one side wall (12), and means for receiving and blocking the corneal tissue (3), characterized in that the device additionally comprises an applanation lid (13) for covering an opening of the device opposite the transparent base (11), the applanation lid (13) comprising: a transparent window (131), and a support (132) between the window (131) and the side wall (12), the support (132) comprising means for moving the window (131) in translation with respect to the side wall (12) of the device.

FIELD OF THE INVENTION

The present invention relates to the general technical field of medical devices for preservation and/or quality control (imaging, microbiological analysis, etc.) and/or treatment of human or animal corneal tissue previously removed from a donor. This corneal tissue is composed of the cornea and a peripheral scleral ciliary zone surrounding the cornea.

Such preserved corneal tissue can be used to perform corneal transplantation, or for ex vivo experimentation.

More precisely, the present invention relates to the technical field of devices for preserving corneal tissue comprising:

-   -   means for receiving and locking corneal tissue,     -   means for circulating one (or more) fluid(s) (liquid or gaseous)         for preserving corneal tissue.

BACKGROUND OF THE INVENTION

Various devices for preserving corneal tissue have already been proposed.

Document U.S. Pat. No. 5,789,240 describes a device for preserving corneal tissue simulating the anterior chamber of the eye. This device does not permit sterile circulation of a preserving fluid on both sides of the corneal tissue, i.e., on both the epithelial and endothelial sides of the corneal tissue. In addition, because the walls of the device are not transparent, it is not possible to perform corneal tissue imaging or a laser cutting procedure without opening the device. As a result, the survival time of the corneal tissue is short and incompatible with use for corneal transplantation.

Document WO 2014/140434 describes a corneal tissue preservation device to address these drawbacks.

The device according to WO 2014/140434 includes:

-   -   means for receiving a corneal specimen including a first         part—called the “intermediate component”—comprising a hole of         the diameter of the cornea surrounded by a circular groove and         an edge forming a housing intended to receive the corneal         specimen, the housing ensuring the correct centering of the         corneal specimen when it is placed in the device and allowing         the corneal specimen to remain stable when the device is opened         in the operating theatre;     -   means of confinement comprising a second part—called the         “endothelial lid”—comprising a hole the diameter of the cornea         surrounded by an edge intended to entrap the corneal specimen by         crushing a scleral ciliary zone of the corneal specimen onto the         circular groove of the intermediate component,         the means for receiving and entrapping the corneal specimen         sealingly locking the scleral ciliary zone surrounding the         cornea to delimit a separate endothelial chamber and epithelial         chamber in which a preservation medium can circulate with an         overpressure in the endothelial chamber.

The preservation device described in WO 2014/140434 has many advantages and allows long-term preservation of corneal tissue.

The present invention is intended to improve the device described in WO 2014/140434.

In particular, a purpose of the present invention is to provide a storage device in which:

-   -   the corneal tissue can be stored for a longer period,     -   the quality of corneal tissue and its imaging are improved,     -   the handling of the corneal tissue contained in the device is         facilitated (in particular with regard to the lamellar or         vertical cutting of the corneal tissue in a closed vessel by         laser at the corneal bank or in the operating theatre (thanks to         an applanation cover which will be described hereinbelow), its         mechanical vertical trepanation in the operating theatre (thanks         to a trepanation cover which will also be described         hereinbelow), etc.

BRIEF DESCRIPTION OF THE INVENTION

For this purpose, the invention provides a medical device for preservation of previously removed corneal tissue, the device comprising an at least partially transparent base, at least one side wall, means for receiving and locking corneal tissue, and an applanation lid for covering an opening opposite the base, the applanation lid including a transparent window, remarkable in that the applanation lid further includes a support between the window and the side wall, the support comprising means for translatory displacement of the window relative to the side wall of the device.

Preferred but non-limiting aspects of the medical device according to the invention are the following:

-   -   the support can be made of an elastically deformable soft         material;     -   the device is configured such that, in use, the receiving and         locking means define, together with the base, the corneal         tissue, the side wall and the lid, an endothelial chamber and an         epithelial chamber, the endothelial and epithelial chambers         including inlet and outlet ports for the circulation of a gas         and/or a preserving fluid, the support which may include a         release zone for receiving part of the gas and/or preserving         fluid contained in the epithelial chamber when the window is         moved translationally towards the base;     -   the means for translational movement may comprise an annular         bellows having at least one pleat;     -   the annular bellows can be made of a shape-reversing material;     -   the side wall comprises an annular rib; this annular rib is         intended to cooperate with means for fastening the lid (such as         fastening hooks) to allow the removable fastening of the lid to         the side wall,     -   the device may further comprise a trepanation lid including a         circular outer casing, a blade holder, and a cylindrical blade,         the applanation lid being replaceable with the trepanation lid         to cover an opening opposite the base (11); in which case the         medical device is a kit including both the applanation lid and         the trepanation lid, the trepanation lid being mountable on the         side wall in place of the applanation lid, for example to         perform corneal tissue cutting in the operating theatre,     -   the outer casing of the trepanation lid may have at least two         fastening hooks at its periphery, the fastening hooks extending         radially and being intended to cooperate with the rib provided         in the outer face of the side wall; this facilitates the         installation of the trepanation lid,     -   the side wall may comprise a peripheral flange, and the base may         comprise clipping means, said clipping means consisting of at         least two elastic tabs for cooperation with the peripheral         flange;     -   the clipping means may comprise at least three elastic tabs         uniformly distributed around the side wall.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and features of the device according to the invention will become clearer from the description that will follow of several alternative embodiments, given by way of non-limiting examples, from the appended drawings wherein:

FIG. 1 is a schematic representation of corneal tissue preservation chambers (endothelial chamber and epithelial chamber),

FIGS. 2, 3 and 4 are schematic representations of a cartridge incorporating the corneal tissue preservation chambers and all the necessary peripherals (channels, reservoir, recovery compartment, gas-controlled valves, channels and propellant connection tip),

FIG. 5 is a schematic representation of a docking station adapted to receive a plurality of cartridges as shown in FIGS. 2 to 4,

FIGS. 6 and 7 are functional representations of two alternative embodiments of cartridges,

FIG. 8 is a schematic representation of a cartridge switching system,

FIGS. 9 and 10 are schematic representations of a medical device applanation lid,

FIGS. 11 and 12 are partial schematic representations of the medical device. These figures illustrate the principle of operation of the applanation lid shown in FIGS. 9 and 10,

FIGS. 13 and 14 are schematic representations showing a trepanation lid of the medical device.

DETAILED DESCRIPTION OF THE INVENTION

Various examples of the medical device will now be described with reference to the figures. In these different figures the equivalent elements are designated by the same numerical reference.

1. General Information about the Device

1.1. General Structure of the System

With reference to FIG. 1, preservation chambers 1 of the device, in particular endothelial and epithelial chambers, have been illustrated, these preservation chambers 1 being delimited by:

-   -   previously removed corneal tissue on the one hand, and     -   a base 11, at least one side wall 12 and a lid C of the device         on the other hand.

The base 11 is preferably made of a material transparent to light radiation, either in its entirety or in an area opposite the lid C.

The lid C can consist of:

-   -   a “standard” lid (including a covering wall to cover an upper         opening in the side wall 12 opposite the base, and peripheral         fastening means) this standard lid has at least one transparent         part facing the corneal tissue, or     -   an applanation lid 13 for example for laser cutting or imaging         corneal tissue, or     -   a trepanation lid 15 for mechanical trepanation of corneal         tissue, or     -   any other type of lid depending on the intended application.

In the embodiment illustrated in FIG. 1, the preservation chambers 1 have a cylindrical shape. However, the preservation chamber 1 may have other shapes (for example parallelepiped, ovoid, etc.) depending on the intended application.

The base 11, the side wall 12 and the lid C can be made in two or more pieces.

For example, in a first embodiment, the base 11 and the side wall 12 are made in one piece. In this case the base 11 is transparent to allow inspection of the corneal specimen (visual as well as by any optical or ultrasonic means), while the lid C consists of an independent part intended to close the upper opening. The lid C also has at least one transparent central part to allow inspection of the corneal specimen visual as well as by any optical or ultrasonic means).

In a second embodiment, the lid C and the side wall 12 are made in one piece.

Finally, in a third embodiment, and as shown in the alternative embodiments illustrated in FIGS. 9-10 and 13-14, the base 11, the side wall 12 and the lid can consist of three independent parts for assembly. In these different alternatives, the base 11 includes clipping means 111 intended to cooperate with a peripheral flange 122 extending radially outwards from the side wall 12.

The clipping means 111 may comprise two (or more) spring-back elastic (for example shape memory) tabs arranged opposite each other and extending substantially perpendicular to the base 11. When the base 11 comprises more than two elastic tabs, these may be uniformly distributed at different positions of the base 11 so as to surround the side wall 12. The fact that the elastic tabs are uniformly distributed makes it possible to apply a substantially homogeneous force over the entire periphery of the side wall 12.

Each elastic tab is provided with a hooking lip at its free end. Each hooking lip projects in a horizontal plane (parallel to the base 11). Of course, clip elements 111 could be of any other type known to the skilled person.

Advantageously, each elastic tab can include a zone of weakness allowing the elastic tab to break when a force (above a threshold value) is applied in a direction opposite to the hooking lip. This makes it easier to release the side wall 12 in order to free the corneal tissue during a corneal graft surgery procedure, for example.

It is quite obvious to the skilled person that in certain embodiments, the elastic tabs can be devoid of zones of weakness. Therefore, in these embodiments, the elastic tabs can be moved apart (without breaking) to allow the removal and replacement of the lid C at the time of collection, for example when the centering of the cornea has not been carried out correctly.

1.2. Device Integration

The medical device may consist of a cartridge with the preservation chambers 1 for receiving the corneal tissue 3.

The cartridge 2 can be parallelepiped and include:

-   -   one (or more) input connection terminal(s) 21 opening to the         outside of the cartridge 2, and intended to be connected to         means for linking a docking station 6 (which will be described         hereinbelow with reference to FIG. 5), said linking means being         connected to one (or more) source(s) of pressurizing gas,     -   one (or more) control connection terminal(s) 22 leading to the         outside of the cartridge 2, and intended to be connected to the         connecting means of the docking station 6,     -   a storage compartment 24 forming a housing for a preserving         fluid (which can be contained in a medical pouch type         container),     -   a recovery reservoir 25 intended to collect user fluids from the         preservation chambers 1,     -   a switching system 26 including one (or more) deformable         valve(s) for controlling the flow rate of the preserving fluid         inside the preservation chambers 1, the pressurization of the         preservation chambers, the circulation of the preserving fluid,         etc.     -   circulation channels (for preserving fluid or gas) 23 extending         inside the cartridge 2 between:         -   the input connection terminal(s) 21 and the storage             compartment 24,         -   the storage compartment 24 and the preservation chambers 1,         -   the control connection terminal(s) 22 and the switching             system 26, and between         -   the preservation chambers 1 and the recovery reservoir 25     -   these channels 23 are advantageously etched in the body of the         cartridge itself in order to avoid the problems associated with         conventional wiring (such as connections, joints, lengths of         tubing, porosity of tubing, especially gas tubing, etc.).

Advantageously, each cartridge can include a radio-frequency identification (RFID) tag to ensure the traceability of the corneal sample during its storage.

Each cartridge may further include an inflation balloon, with manual actuation of the inflation balloon increasing the pressure in the storage compartment 24 and then in the preservation chambers when the cartridge 2 is disconnected from the docking station 6.

1.3. Docking Station

The fact that the device integrates the preservation chambers 1 and its peripherals in the form of a cartridge 2 facilitates handling and storage, for example in a docking station that allows the preservation chambers to be maintained at a desired temperature, at a controllable pressure and in a controlled atmosphere (percentages of N₂, O₂, CO₂ in particular). This integration also improves the sterility of the interior of the medical device, in particular by separating the circuits of gas and preserving fluid(s) and connecting them by terminals (without tubing).

As a guide, an example docking station is shown in FIG. 5. The docking station 6 contains temperature control means to maintain its interior volume at a set temperature.

This docking station 6 is, for example, a commercially available preservation oven. The inner volume of the docking station 6 consists of a support structure with racks 7 each for receiving one cartridge 2.

Each rack 7 has linking means intended to be connected to the input and control terminals 21, 22 of its associated cartridge 2 to allow the gas supply of the latter. Insertion of the cartridge into the rack 7 allows the connection means to be connected to the input terminals. Each rack 7 may also include means for checking the presence of the cartridge and/or means for reading/writing the RFID tag.

The docking station 6 also contains an injection device 43 such as a diaphragm pump or other system for producing compressed air or gas to supply each cartridge 2.

The docking station includes a pressure regulation control means, as well as a pneumatic switching sequential control means of the switching system 26. These monitoring and control means are common to all the cartridges 2 and are sequentially assigned to each of the cartridges 2 via the connecting means contained in each of the racks into which the cartridges are inserted. This is in order to advantageously mutualize the pressure regulation and the flow of preserving fluid within each of the cartridges 2 present in the docking station 6.

The docking station 6 can be connected (via a wired or wireless link) to a remote control unit such as a personal computer, or a touch tablet, or any other control unit known to the skilled person.

When inserted into the docking station 6, the cartridge 2 is in long-term storage mode, with regulated pressure and flow. When the cartridge 2 is removed from the docking station 6, the fluid flow is stopped, and the integrated switching system 26 advantageously allows the preserving fluid to be pressurized in its internal circuits independently. This, together with the consequent reduction in weight and volume, makes the cartridge extremely mobile, allowing it to be moved from one point to another.

Different elements of the medical device according to the invention will now be described in more detail.

2. Preservation Chambers

2.1. Corneal Tissue Locking Means

The device comprises means 14 for locking the corneal tissue 3 in position so that the epithelial side of the corneal tissue 3 extends opposite the lid 13.

In the embodiments illustrated in FIGS. 9 and 10, the locking means define, together with the corneal tissue 3, the preservation chambers known respectively as the “endothelial chamber” 4 and the “epithelial chamber” 5.

Specifically, the locking means include:

-   -   a base 141 on which the base 11 is fixed, and intended to         receive the corneal tissue 3,     -   a flexible retaining ring 142 to hold the corneal tissue 3 in         position on the base 141.

The endothelial chamber 4 and the epithelial chamber 5 may each have at least three ports:

-   -   an inlet port for the injection of preserving fluid,     -   an outlet for the discharge of the preserving fluid, and     -   a technical port for taking a fluid sample (for example for         analysis) or injecting additional substances into the chamber.

The inlet and outlet ports of the two chambers 4, 5 allow a preserving fluid to be circulated and renewed to optimize the preservation of corneal tissue.

Advantageously, the composition of the preserving fluid injected into the epithelial chamber 5 may be different from the composition of the preserving fluid injected into the endothelial chamber 4.

2.1.1. Base

The base 141 is the cartridge base. It has a central opening whose upper edge 143 (opposite base 11) is intended to receive corneal tissue. The diameter of the central opening is preferably approximately equal to the diameter of a cornea (typically between 9 and 13 millimeters in diameter).

The surface of the upper edge 143 of the base 141 (i.e. opposite the base 11) may be curved to conform to the curvature of the corneal tissue 3. In particular, the surface of the upper edge 143 may have a truncated cone shape, or even a toric shape.

The corneal tissue 3 is intended to be placed on the base 141 so that the peripheral scleral ciliary zone of the corneal tissue 3 comes into contact with the upper edge 143.

The base 141 also includes (at least) one inlet port and (at least) one outlet port. The inlet and outlet ports allow the preserving fluid 41 to flow into the endothelial chamber 4, the walls of which are defined by:

-   -   the base 11 of the device,     -   the base 141,     -   the retaining ring 142, and     -   the corneal tissue 3.

2.1.2. Retaining Ring

The retaining ring 142 extends perpendicularly inwards from the side wall 12.

The hole in the retaining ring 142 can be elliptical or circular. In the case of a circular hole, the inner diameter of retaining ring 142 is preferably approximately equal to the diameter of a cornea (typically between 9 and 13 millimeters in diameter) and approximately identical to the central opening of the base. Thus, the sclera of the corneal tissue 3 is intended to come into contact with the inner edge 144 of the retaining ring 142.

The retaining ring is advantageously made of a flexible material so that it can be bent by elastic deformation to conform to the profile of the upper edge 143. This also allows the retaining ring 142 to absorb any irregularities in the scleral ciliary zone by squeezing to a greater or lesser extent to ensure calibrated force support and sealing in the contact area between the corneal specimen 3 and the retaining ring 142.

The retaining ring 142 can be attached to the side wall 12 or can be detachably mounted on side wall 12. For example, in the embodiment illustrated in FIGS. 9 and 10, the inner side of the side wall 12 has an inwardly extending annular border 121. This annular border 121 is intended to press the retaining ring 142 against the base 141 when side wall 12 is assembled on the base 11 of the device.

Of course, the annular border 121 can be replaced by a plurality of studs arranged on the inside of the side wall 12 and extending radially inwards therefrom.

2.1.3. Principle of Operation

The principle of operation of the locking means 14 is as follows.

The corneal tissue 3 is placed on the base 141 so that the endothelial side of the corneal tissue 3 lies opposite the base 11. The peripheral scleral ciliary zone of the corneal tissue 3 comes into contact with the upper edge 143 of the base 141.

The retaining ring 142 is placed on the corneal tissue 3 The inner edge 144 comes into contact with the peripheral scleral ciliary zone of the corneal tissue 3.

The side wall 12 of the device is assembled on the base 11. Specifically, the side wall 12 is moved translationally between the clipping means 111. The shape-reversing spring tabs move out of their original position when the peripheral flange 122 passes over the hooking lips.

Approaching the base 11, the annular border 121 of the side wall 12 tends to press the retaining ring 142 against the base 141. The translational movement of the side wall 12 induces a translational movement of the retaining ring 142 towards the base 141 so as to lock the corneal tissue 3 in position.

The fact that the movement of the retaining ring is rectilinear (i.e. translation of the retaining ring 142 towards the base 141) rather than helical (for example when the retaining ring is screwed in) limits the risk of twisting the corneal tissue 3 when it is locked in position. This improves the viability of the corneal tissue thus preserved. Indeed, a twisting of the corneal tissue induces the appearance of folds in the corneal tissue, these folds causing an accelerated degradation of the cells and corneal tissue 3.

When the edge reaches a position in which the peripheral flange 122 extends under the hooking lips, the elastic tabs return to their respective initial positions so that the hooking lips press the side wall against the base 11 by applying a pressing force to the peripheral flange 122.

The scleral ciliary zone is compressed between the upper edge 143 of the base 141 and the inner edge 144 of the retaining ring 142 to hold the corneal tissue 3 in position in the preservation chambers. The use of clipping means for assembling the side wall 12 against the base 11 ensures that a constant compression force of the scleral ciliary zone is applied from one medical device to another.

This makes the operation of inserting corneal tissue into the device repeatable and easily performed by an operator inexperienced in the use of the device.

The reader will have understood that the above operating principle has been presented with reference to a medical device in which the retaining ring 142 is not attached to the side wall 12. It is quite obvious to the skilled person that the steps of placing the retaining ring 142 and the side wall 12 are carried out simultaneously in the case of a medical device in which the retaining ring 142 is attached to the side wall 12.

2.2. Preservative Fluid Supply

Once the corneal tissue has been installed and the preserving fluid circulation has been started, the corneal tissue can be preserved for several weeks prior to its use for corneal transplantation or ex vivo experimentation.

To increase the storage life of the corneal specimen, a preserving fluid is used.

The management of the supply of preserving fluid to the device is ensured by the following set of elements:

-   -   At the cartridge 2:         -   the inlet connection terminal(s) 21 and control terminal(s)             22 intended for connection to one (or more) source(s) of             pressurizing gas,         -   the storage compartment 24 forming a housing for a             preserving fluid: the preserving fluid can be contained             directly in the compartment 24 or be contained in a             container (for example of the medical pouch type) arranged             in the compartment 24,         -   the recovery reservoir 25 intended to collect the user             fluids from the preservation chambers 1,         -   the switching system 26 for controlling the circulation of             the preserving fluid,         -   The circulation channels 23 extending into the cartridge 2,     -   At the docking station 6:         -   the linking means for connection to the input and control             terminals,         -   an injection device 43 using compressed gas to distribute             the fluid 41 and control the switching system 26.

This set of elements allows the circulation and renewal of the preserving fluid in the endothelial chamber 4 and/or in the epithelial chamber 5. This set of elements also allows the pressure inside the endothelial and epithelial chambers 4, 5 to be varied so as to have a continuous overpressure in the endothelial chamber 4. This overpressure may correspond to the pressure physiologically encountered by the cornea on the endothelial side, or it may correspond to any other pressure chosen by the user.

Advantageously, if the compartment 24 of the cartridge 2 comprises two distinct preserving fluids (for example contained in separate compartments of compartment 24 or in medical pouch-type containers housed in the compartment 24) each associated with a respective chamber, then the composition of the preserving fluid circulating in the endothelial chamber 4 may be different from the composition of the preserving fluid circulating in the epithelial chamber 5 (for example a mixture of preserving fluid+gas of controlled composition N₂ O₂ CO₂). This makes it possible to have a preservation medium adapted to each cell type (endothelial and epithelial).

The injection device 43 allows the injection of pressurized gas into the storage compartment 24 and the switching system 26. The injection device 43 can be contained in the docking station 6 and connected to the cartridge 2 via the connection terminals 21, 22 of the cartridge 2. The injection device 43 is, for example, a gas compressor, or compressed gas cartridge, or a connection to a compressed air network, making it possible to generate two distinct pressures: a regulated pressure intended for pressurizing the endothelial chamber via a switching element 432 (such as a valve), and an operating pressure intended for controlling the fluid switching elements 26 via the connections 22.

The use of a pressurized gas injection device 43 (instead of the roller pump described in WO 2014/140434) separate from the cartridge 2 has many advantages.

In particular, it makes it possible to:

-   -   reduce the size and weight of the cartridge 2 integrating the         preservation chambers,     -   increase the service life of the cartridge 2 (by avoiding of the         hose wear problem linked to the use of a peristaltic pump),     -   reduce the heat generated by the pump (the motor of a         peristaltic pump emits more calories than a compressed gas         injection device),     -   reduce “jerks” in the regulation of preserving fluid flow and         pressure,     -   regulate more precisely the pressure and flow rate in the         chamber(s),     -   improve the energy efficiency of pressurization-circulation,     -   facilitate the realization of an independent fluidic circuit in         the epithelial chamber, in order to expose it to a preserving         fluid different from the endothelial chamber,     -   facilitate intermittent exposure of the corneal specimen 3 to a         gas flow (such as air or an atmosphere controlled by oxygen         and/or carbon dioxide enrichment) to improve the quality of the         corneal tissue and/or facilitate its imaging (possibility of         filling the epithelial chamber with gas (for example air) which         allows the use of instruments for optical measurement of the         graft (pachymetry or detection of optical aberrations due to         refractive surgery of the donor, as an example by optical         coherence tomography, or specular microscopy),     -   limit the risk of contamination by the external environment,     -   facilitate the transport of the device (from the sampling site         to the corneal bank and from the bank to the operating theatre)         by integrating all the elements necessary for the preservation         of corneal tissue in the device.

Pressurized gas is used to propel the preserving fluid 41 into the preservation chambers.

2.2.1. “with Contact” Type Fluid Supply

FIG. 6 shows an embodiment in which the preserving fluid 41 is stored directly in the storage compartment 24 for a “contact type” fluid supply.

In this case the compressed gas from the injection device is introduced directly into the compartment 24 to propel the preserving fluid 41 to the endothelial chamber 4 (gas and fluid mix in this configuration). The advantage of this solution is that it allows exchanges between the gas and the preserving fluid (for example enrichment with oxygen and/or carbon dioxide).

In the embodiment illustrated in FIG. 6, the cartridge 2 comprises a switching element 432 and a filter 433 between the input terminals 21 and the control terminals 22 on the one hand, and the storage compartment 24 on the other hand.

In this embodiment, the operating principle is as follows. The injection device 43 provides:

-   -   a compressed propellant gas regulated in pressure via the inlet         terminal 21, this propellant gas being intended to be injected         into the storage compartment 24, and     -   a compressed control gas via the control terminal 22, which is         used to control the opening and closing of the switching element         432,

The switching element 432 controls the injection of the propellant gas into the storage compartment 24. Specifically, a compressed control gas (forming a pneumatic control) is applied to the control terminal 22 a to allow the pressurized propellant gas injected via the inlet terminal 21 to propagate to the storage compartment 24.

The filter 433 sterilizes the compressed propellant gas from the injection device 43 prior to its introduction into the compartment 24. The propellant gas injected into the storage compartment pushes the preserving fluid 41 to the endothelial chamber 4. The medium initially contained in the endothelial chamber 4 (for example air when the device is closed), is expelled towards the epithelial chamber 5.

2.2.2. Non-Contact Type Fluid Supply

With reference to FIG. 7, an embodiment has been illustrated in which the preserving fluid 41 is contained in a container 42 housed in the storage compartment 24 for a “non-contact” type fluid supply. The container 42 may consist of a medical pouch comprising two flexible or soft sheets superimposed and welded at their periphery.

An inflatable balloon to receive the propellant gas is also housed in the storage compartment 24. This inflatable balloon allows pressure to be exerted on the outer faces of the walls of the container 42 when it expands to propel the preserving fluid 41 to the endothelial chamber 4 (gas and fluid do not mix in this configuration).

In the embodiment illustrated in FIG. 7, the cartridge 2 has a switching element 432 between the terminals 21,22 and the storage compartment 24.

In this embodiment, the operating principle is as follows. The injection device 43 supplies the compressed gases (propellant and control) to the input and control terminals 22.

The switching element 432—controlled by the pressure sensor—controls the injection of propellant gas into the storage compartment 24. Specifically, a control compressed gas (forming a pneumatic control) is applied to the control terminal 22 a to allow the pressurized propellant gas injected via the inlet terminal 21 to propagate to the storage compartment 24.

The compressed propellant gas is introduced into the inflatable balloon, which tends to press against the walls of container 42 as it expands.

This pressure exerted by the inflatable balloon on the container 42 induces the ejection of preserving fluid 41 to the endothelial chamber 4.

2.2.3. Switching System

The injection device 43 also supplies control compressed gas to the switching system 26 via the control terminals 22 b, 22 c, 22 d. This control gas is used to control the switching system 26.

FIG. 8 shows an example of a switching system 26 to control the flow and pressure of the preserving fluid within the endothelial chamber 4 and epithelial chamber 5.

The switching system 26 consists of valves V1, V2, V3 that are pneumatically operated (by means of control gas injected into the control terminals 22 b, 22 c, 22 d).

These valves V1, V2, V3 can consist of elastomer valves which are deformable under the effect of pneumatic pressure. These valves V1, V2, V3 have the particularity of being closed in the absence of pilot pressure. This allows the cartridge 2 to remain under pressure when it is removed from its rack 7.

The valves V1, V2, V3 are operated in a sequence performed in five steps.

In a first (so-called initial) step, the three valves V1, V2, V3 are closed at rest and no liquid can flow through the switching system 26.

In a second step, the injection device 43 emits a control gas into the control terminals 22 b, 22C. The first and second valves V1, V2 open under the action of the control gas. This allows the preservation medium to enter the second valve V2 via the first valve V1.

In a third step, the injection device 43 stops the emission of control gas in the control terminal 22 b. The first valve V1 closes, thus trapping a quantity of preserving fluid in the dead volume of the second valve V2.

In a fourth step, the injection device 43 emits a control gas into the control terminal 22 d. The third valve V3 opens to release the fluid contained in the second valve V2.

In a fifth step, the injection device 43 stops the emission of control gas in the control terminal 22 c. The second valve V2 closes by expelling the fluid contained in its dead volume to the third valve V3.

The return to the initial step results in the closing of the third valve V3 which in turn expels the fluid contained in its dead volume towards the epithelial chamber 5.

A complete cycle displaces a volume of fluid equivalent to the dead volume of one valve, and in particular the dead volume of the second valve V2. It is therefore the dead volume of the second valve V2, and the repetition frequency of the sequence that will determine the flow of fluid in the cartridge 2.

2.3. Lid

As described above, the device comprises a lid that can be sealingly engaged in the side wall 12 to delimit the epithelial chamber.

Different types of lids can be used, including an applanation lid 13 or a trepanation lid 15. Specifically, if the applanation lid is mounted on the side wall, it can be replaced by a trepanation lid, for example for cutting corneal tissue (and vice versa). Therefore, the medical device may include a number of different lids that can be mounted on the side wall 12 depending on the needs of the practitioner.

Different types of lids will now be described in more detail.

2.3.1. Applanation Lid

With reference to FIGS. 9 to 12, an example of an applanation lid 13 according to the invention is illustrated. The applanation lid 13 allows the corneal tissue 3 to be flattened for imaging or processing in a closed environment (i.e. without exposing the corneal tissue 3 to the external environment) so as to avoid any risk of contamination.

The applanation lid 13 consists of a translationally movable window 131 and a support 132 for connecting the window 131 to the side wall 12 of the device.

2.3.1.1. Window

The window 131 is made of a material that is transparent to radiation (light and electromagnetic) or ultrasound.

This allows a user to observe (for example using a specular reflection microscope or an OCT or ultrasound device) and/or treat (for example using a laser) the corneal tissue 3 from outside the device without opening it (commonly referred to as a “closed vessel”).

The window 131 can be flat or curved. It has an annular bead on its periphery. The annular bead is intended to cooperate with an annular groove in the support 132 to fix the window 131 tightly to the support 132.

2.3.1.2. Support

The support 132 is detachably attached to the side wall 12 of the device.

The support 132 allows the window 131 to be held in line with the corneal tissue 3. Advantageously, the support 132 includes means for translatory movement of the window 131 in relation to the side wall 12 of the device.

Specifically, the support 132 includes means to move the window 131 translationally between:

-   -   a resting position in which the window 131 is distant from the         corneal tissue 3 (see FIGS. 9 and 11),     -   an active position in which the window 131 is in contact with         the corneal tissue 3 to flatten it (see FIGS. 10 and 12).

To move from the rest position to the active position, the user applies (with a microscope or laser or other device) a force in the direction of the corneal tissue 3, perpendicular to the plane containing the window 131 to move the window 131 to the base 11 of the device.

The fact that the window 131 is movable translationally (rather than rotation as proposed in WO 2014/140434) limits the risk of the corneal tissue 3 twisting when the window 131 comes into contact with it to flatten it, as this twisting can damage the corneal tissue 3 as mentioned above.

Advantageously, the support 132 is made of an elastically deformable soft material. This guarantees the tightness of the lid 13 and thus improves the sterility of the device.

The support 132 may include a clearance area to receive a portion of the gas and/or preserving fluid contained in the epithelial chamber 5 when the window 131 is in the active position. This limits pressure variations in the endothelial and epithelial chambers 4, 5 when the window 131 is moved from the rest position to the active position.

In the embodiment illustrated in FIGS. 9 to 12, the support 132 consists of an outer sleeve and the means of translational movement consists of an annular bellows, the sleeve and the bellows being made in one piece.

The sleeve is intended to be pressed onto the inside of the side wall 12 (or alternatively clipped onto an external groove of the side wall 12 by means of anchoring means—such as fastening hooks—mounted on the outer ring).

The annular bellows extends radially inward from the outer sleeve. The free edge of the bellows includes the annular groove intended to cooperate with the annular bead of the window 131 to secure the support 132 and the window 131 together. Of course, an adhesive—such as biocompatible glue—or any other means known to the skilled person can be used to ensure that the window 131 is tightly fixed to the support 132.

The annular bellows may comprise one (or more) pleat(s) (successively). The pleat(s) (generally concavely rounded) allows compression and extension of the bellows as well as flexion on either side of its resting position.

Preferably the annular bellows is shape-reversing, so that when no force is applied to the window 131, it returns to its rest position. Thus, as soon as imaging or treatment of the corneal tissue 3 is completed, the window 131 automatically returns to the rest position without the user having to perform any action. This prevents the corneal tissue 3 from being stored for several weeks in a flattened state, which would partially damage it.

2.3.1.3. Principle of Operation

The operating principle of the applanation lid 13 is as follows.

When the user wishes to image the corneal tissue 3, for example to check the cell and tissue quality of the corneal tissue, she positions a microscope head opposite the window 131 and moves it to the base 11 of the device.

This induces the translational movement of the window 131 towards the base 11 of the device: the pleat(s) of the bellows extend(s).

The displacement of the window 131 towards the corneal tissue induces a decrease in the volume of the epithelial chamber. The pleat(s) of the bellows (which constitutes the zone of release) deforms to receive some of the gas or fluid contained in the epithelial chamber 5. This limits pressure variations in the epithelial chamber 5.

The window 131 comes into contact with the corneal tissue 3, which tends to flatten it when the window 131 is placed against the corneal tissue 3. The window 131 continues to move until the user stops moving the microscope to the base 11 and/or the window comes into contact with the inner edge 144 of the retaining ring 14.

Thus, the applanation lid 13 allows a controlled deformation of the corneal tissue 3 by contact of the window 131 of the lid with the epithelial face of the corneal tissue 3, while keeping the device tight (closed vessel excluding any risk of contamination).

This applanation lid 13 makes it possible to:

-   -   dampen possible pressure variations (by deformation of the         bellows pleat(s))     -   improve the quality of imaging         -   the optical contact of the imaging device with the window             and the corneal tissue eliminates interfaces with the             preserving fluid or air in the epithelial chamber, thus             improving the imaging obtained for example by specular             microscopy, OCT, ultrasound biometry, confocal microscopy or             any other technique known to the skilled person,         -   by flattening the corneal tissue, it is possible to define a             reference surface (flat or curved), and to improve the             imaging possibilities (wider field, suppression of the             natural curvature of the cornea),     -   make a laser incision in the cornea in a closed vessel, whether         parallel to the flat surface (anterior lamellar grafts of         circular or free form (corneal patch) or endothelial grafts)         and/or perpendicular to the surface (transfixation or lamellar         grafts),     -   reduce the risk of trauma to the corneal tissue (no manipulation         of the graft), and to guarantee its sterility by keeping it in a         closed vessel,

2.3.2. Trepanation Lid

With reference to FIGS. 13 and 14, a second type of lid has been illustrated, namely a trepanation lid 15.

The trepanation lid 15 allows a circular incision to be made in the corneal tissue 3. Specifically, the trepanation lid allows a transfixing or non-transfixing (controlled depth) cut to be made in the corneal tissue for transfixing or lamellar grafts.

The trepanation lid 15 includes:

-   -   an outer casing 151 having an axis A-A′, and having a foot part         for its application to the side wall of the device,     -   an inner blade holder 152 movable within the casing 151, and         coaxial to said holder 151,     -   a cylindrical blade 153 also coaxial to the casing 151.

The outer casing 151 has the general shape of a disc. It comprises radially outwardly extending fastening hooks 154 at its periphery. Each fastening hook 154 is intended to cooperate with an annular rib 123 on the outside of the side wall 12 to enable the fastening of the trepanation lid 15 to the side wall 12. The central part of the outer casing 151 comprises a through passage including a thread with a known pitch to accurately quantify the penetration of the blade.

The blade holder 152 is intended to be positioned in the through-passage of the outer casing 151. It consists of:

-   -   a distal end including gripping means to enable a user to         manipulate the blade holder 152, and     -   a proximal end carrying the cylindrical blade 153.

The outer face of the blade holder 152 has, between its proximal and distal ends, a thread complementary to the thread of the outer casing 151.

The operating principle of the trepanation lid 15 is as follows. Once the trepanation lid 15 is fixed on the side wall 12 of the device, the user screws the blade holder 152 on the outer casing 151 using the gripping means. This causes the cylindrical blade 153 to move (very slowly) towards the corneal tissue 3 in a helical movement. The cutting blade consisting of the lower edge of the cylindrical blade 153 penetrates the corneal tissue 3 and allows a circular cut to be made through the epithelial surface, thus minimizing endothelial lesions and with vertical edges.

Advantageously, pressure can be maintained in the endothelial chamber 4 during the entire corneal tissue 3 trepanation operation.

CONCLUSIONS

The invention described above improves the operation of the bioreactor according to WO 2014/140434, the quality of corneal tissue as well as its imaging, and extends its applications to new functions, such as corneal cutting in a closed vessel by laser, corneal trepanation etc.

-   a. The device described above increases the storage life of corneal     tissue. It also improves the quality of the corneal tissue stored.     -   In particular, the arrangement of the locking means, and in         particular the translational movement of the retaining ring 142         in relation to the base 141, prevents the corneal tissue 3 from         twisting and thus the appearance of folds in it.     -   In addition, the presence of clipping means 111 for the assembly         of the side wall 12 on the base 11 ensures that a constant         compressive force is applied to the corneal tissue. This makes         the corneal tissue placement operation repeatable from one         medical device to another. -   b. The device described above also improves the imaging quality of     the corneal tissue 3.     -   In particular, the fact that the applanation lid 13 includes         means for translational movement of the window 131 limits the         risk of the corneal tissue 3 twisting during flattening, as this         twisting can degrade the imaging quality of the corneal tissue         3. -   c. Finally, the device described above makes it easier to manipulate     the corneal tissue 3, especially with regard to its removal from the     device and/or cutting, for example during corneal graft surgery.

In reference to the extraction of the corneal tissue 3, the presence of a zone of weakness on the elastic tabs makes them breakable under the action of a force of intensity greater than a rupture threshold of the zone of weakness. This facilitates the disassembly of the side wall 12 in order to free the corneal tissue 3 during a graft surgery procedure. μ

With reference to cutting of the corneal tissue 3, the fact that a trepanation lid 15 is adaptable on the device (thanks to the fixation hooks and the annular rib) will allow the user to perform an epithelial trepanation which has many advantages compared to a punch trepanation (rapid vertical compression cutting of the punch type which makes non-vertical edges and damages the endothelial cells at the cutting edge) by endothelial way. The device's endothelial pressure regulation system remains fully functional and allows the cornea to maintain its pressurization (thus its physiological shape) during the trepanation. This epithelial trepanation lid makes it possible to:

-   -   carry out a perfectly vertical, total or partial cutting     -   minimize endothelial damage in the case of transfixing cutting.

The reader will have understood that many changes can be made to the medical device described above without materially altering the new teachings and benefits described here. Therefore, all such changes are intended to be incorporated within the scope of the attached claims. 

1. A medical device for preserving previously removed corneal tissue, the device comprising an at least partially transparent base, at least one side wall, receiver for receiving and locking the corneal tissue, and an applanation lid for covering an opening opposite the base, the applanation lid including a transparent window, wherein the applanation lid further includes a support between the window and the side wall, the support having a translator for translating the window relative to the side wall of the device.
 2. The device as claimed in claim 1, wherein the support is made of an elastically deformable soft material.
 3. The device as claimed in claim 1, which is configured such that, in use, the receiver defines with the base, the corneal tissue, the side wall and the lid an endothelial chamber and an epithelial chamber, the endothelial and epithelial chambers including inlet and outlet orifices for the circulation of a gas and/or a preserving fluid, the support comprising a clearance zone for receiving part of the gas and/or the preserving fluid contained in the epithelial chamber when the window is translated towards the base.
 4. The device as claimed in claim 1, wherein the translator comprises an annular bellows having at least one pleat.
 5. The device as claimed in claim 4, wherein the annular bellows is made of a shape-reversing material.
 6. The device as claimed in claim 1, wherein the side wall comprises an annular rib.
 7. The device as claimed in claim 1, which further comprises a trepanation lid including a circular outer casing, a blade holder, and a cylindrical blade, the applanation lid being replaceable with the trepanation lid to cover an opening opposite the base, for example to perform a cutting of corneal tissue.
 8. The device as claimed in claim 7, wherein the side wall comprises an annular rib, wherein the outer casing of the trepanation lid has at least two fastening hooks at its periphery, the fastening hooks extending radially and being intended to cooperate with the rib provided in the outer face of the side wall.
 9. The device as claimed in claim 1, wherein the side wall comprises a peripheral flange and the base comprises a clipper, said clipper consisting of at least two elastic tabs intended to cooperate with the peripheral flange.
 10. The device as claimed in claim 9, wherein the clipping means comprise at least three elastic tabs uniformly distributed around the side wall. 